Conventionally, there has been provided a lighting device to light solid light-emitting elements (semiconductor light-emitting elements) such as LED (light-emitting diode) elements or organic EL (electro-luminescence) elements (see, e.g., Japanese Unexamined Patent Application Publication No. 2012-014879). A lighting device disclosed in the above-mentioned reference includes a power-factor correction circuit and a power conversion circuit. The power-factor correction circuit is connected to an AC power source. The power conversion circuit performs power conversion on the output from the power-factor correction circuit to supply current to solid light-emitting elements, thereby lighting the solid light-emitting elements.
The lighting device disclosed in the above-mentioned reference further includes an abnormality detection circuit and a control circuit. The abnormality detection circuit detects abnormality (such as short-circuit and open-circuit) in the solid light-emitting elements. When abnormality in the solid light-emitting elements is detected by the abnormality detection circuit, the control circuit stops the operation of the power-factor correction circuit or suppresses the output of the power-factor correction circuit.
In order to regulate the current supplied to the solid light-emitting elements to be constant, the power conversion circuit of the above-mentioned reference is configured as a step-down chopper circuit having a switching element (a semiconductor element). Accordingly, when the switching element has a short-circuit failure, current is continuously supplied from the power-factor correction circuit to the solid light-emitting elements, and thus the solid light-emitting elements produce heat. The abnormality detection circuit in the above-mentioned reference is merely to detect abnormality in the solid light-emitting elements, but is not able to cope with a short-circuit failure of the switching element.